Improvement in spiral springs



J. LUDLUM. SPIRAL-SPRINGS.

No. 194,157. Patented Aug.14,1877.

[Ky/Z ATTORNEYS.

UNITED STATES PATENT OFFICE.

JAMES LUDLUM, OF POMPTON, NEW JERSEY.

IMPROVEMENT IN SPIRAL SPRINGS.

Specification forming part of Letters Patent No. 194,157, dated August 14, 1877; application filed May 28, 1877.

- into any required relation to the axis of the spiral; .the object being to so dispose the metal of which the spring is made as to utilize it to the fullest extent, and also to economize space.

In Fig. 1,A is a spiral spring, made from a bar of steel having a peculiar form, which is fully shown in the enlarged section, Fig. 2. This bardifl'ersfrom a round bar in having its inner surface flattened at B, and having the projecting rounded cornersaat opposite sides of the flattened portion, and in extending the side b, which is opposite the flattened-side B.

The idea of the plan on which the bar is made is to bring the vertical diametrical line of a round bar nearer the axis of the spiral. To accomplish thisthe natural method would be to make one side of the bar flat, and add to the diameter of the bar to compensate for the deficiency in material due to flattening the side. object; but it is more efl'ectively accomplished by adding to the bar at the point a a and b, rendering it almond-shaped. The transverse section of the bar has the general form of a triangle having two similar curved sides and a right base, and having all of the corners rounded.

Having thus described my invention, I claim as new and desire to secure by Letters Patent- A spiral spring consisting of a coiled steel bar having convex sides and flattened on one of its edges, substantially as shown and described, for the purpose specified.

JAMES LUDL'UM.

Witnesses: I

O. SEDGWICK, ALEX. F. ROBERTS.

This plan partly accomplishes the 

